Originally Posted by Mick Scarborough
Biological control is actually simple if not a bit cruel. Koi. Simply put Koi in the pond, river etc and they eat the hyacinth roots. They multiply like crazy and devour the entire hyacinth patch rapidly and kill it off. The cruel part is after the hyacinth is dead, the koi starve to death.
...starve to death is one way of looking at it. Another way is rendering the "starved" koi as a part of the food chain for bass.